Shoe bottom pressing machine



March 28, 193 9. H. B. NEWHALL SHOE BOTTOM PRESSING MACHINE Filed July 28, 1937 Patented Mar. 28, 1939 UNITED STATES PATENT OFFECE 2,151,712 SHOE BOTTOM PRESSING MACHINE Application July 28, 1937, Serial No. 156,189

r 7 Claims.

This invention relates to means for maintaining pressure in hydraulic cylinders and is illustrated as embodied in a machine of the type disclosed in Letters Patent of the United States No. 2,047,185, granted July 14, 1936, upon an application of Milton H. Ballard et al.

In machines of this type pressure is applied to shoes to effect a cement sole-attaching operation by movement of a piston in a cylinder to which liquid under pressure is admitted. Due to compression of the materials under pressure or to slight leakage of the valves or other connections by which the pressure fluid is applied or controlled, the pressure in the cylinder may drop before the time necessary for effecting a satisfactory cement sole-attaching operation has elapsed.

It is an object of this invention to provide means for maintaining the pressure in the cylinder substantially at its maximum throughout the period during which pressure is applied.

As illustrated herein, the piston is made in two parts. One part, which slides freely in its cylinder, is connected to the usual pressure-applying mechanism, and the other part, which carries the piston ring, is mounted for limited movement relatively to the first part and is held separated therefrom by a series of stiff compression springs. When fluid pressure is applied to the part of the cylinder carrying the rings, it is forced toward the part through which pressure is applied to the shoe, the springs being compressed and the two parts of the piston brought substantially together. If, due to leakage or compression of the work, the pressure in the cylinder diminishes, the springs expand and maintain the pressure necessary for a successful cement sole-attaching operation.

In the drawing,

Fig, 1 is a view, partly in section, of mechanism embodying the present invention;

Fig. 2 is an exploded view of parts shown in Fig. 1; and

Fig. 3 is a view on the line III-III of Fig. 1.

The machine in which the present invention is embodied comprises, as disposed in the abovementioned patent, a pad box IE in which is a pad l2 to receive a sole l4 upon which a shoe [6 is to be pressed. An abutment l8 engages the forepart of the shoe, and an abutment 28 engages the top 22 of a last in the shoe. The abutments I8, 28 are carried respectively by two levers both pivoted at 24 to an upright 26, the rear arms of the levers 28, 30 overlying the ends of a lever 32 which is pivoted between its ends at 34 on ears 36 projecting from the top of a piston 38 fitted to slide freely in the cylinder 40. A rod 42 passes through a transverse hole in the piston 38 and through vertical slots 44 in the side walls of the cylinder 40. To the projecting 5 ends of the rod 42 tension springs 46 are attached for drawing the piston downwardly after it is raised.

To provide the pressure-restoring mechanism of the present invention, the piston is made in 10 two parts. Below the part 38 is a separate part 48 separated thereform by a small space 58. Further separation of the parts 38, 40 is prevented by a bolt 52 havinga head 54 which is countersunk inthe part 48, the bolt extending l5 centrally through the part 38 and being provided at its upper end with a nut 56. The bolt is provided with an elongated slot 58 to receive the rod 42, the slot extending lengthwise of the bolt 52 sufficiently to permit the space between 20 the parts 38, 48 of the piston to be taken up. The parts 38, 48 of the piston are maintained in separated relation as far as the bolt 52 permits by a series of helical compression springs 68 seated in vertical bores in the part 38 of the piston with their lower ends resting against the part 48 of the piston. The number and strength of these springs are so selected that only when substantially the maximum pressure is applied to the piston can the part be forced into contact with the part 38. If now, for any reason, there is a reduction of pressure beneath the piston, the springs will expand slightly and maintain the pressure on the work substantially up to the maximum.

The lower face of the part 48 of the piston is grooved peripherally at El to receive an annular packing ring 62 which, as shown, is U-shaped in cross-section and may be made of rubber or rubber-like material which will withstand the action of the pressure liquid, which usually is oil. The packing ring 62 is disposed in the groove 6! with a groove 63 formed by the U-shaped cross-section of the ring opening downwardly, as shown in Fig. 1. The outer wall of the packing ring E2 is maintained against the wall of the cylinder by an expanding ring 64. A flat ring 66 is placed in the groove 63, and the ring 66 is held in place to hold the packing ring 62 in its groove and the ring 64 is held in position to act on the outer wall of the ring 52 by a retaining plate 68 which is secured by a screw III to the head 54 of the bolt 52. The retaining plate 68 has about its periphery lugs 12 which are bent at right angles to the plate and lugs 14 which are bent at a less 5 angle. When the retaining plate 68 is in place, the lugs 12 engage the flat ring 66 to hold it and the annular packing ring 62 in place and the lugs 14 overlying the ring 64 to hold it in operative position.

The pressure liquid is admitted through a pipe 16 and acts to raise the piston 38, 48 as a Whole, thereby lifting the rear arms 28, 30 of the abutment-carrying levers and causing the abutments 20, 22 to press the shoe and sole against the pad l2. As the pressure builds up, the part 48 of the piston moves relatively to the part 38, compressing the springs 60 and taking up some or all of the space between the piston parts. The oil supply pipe 16 is then closed and the shoe remains for a time under pressure. If, during this time, the applied pressure diminishes for any reason such as above suggested, the springs 50 expand and maintain substantially the same pressure upon the work.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a machine for applying pressure to workpieces, the combination of a support to receive a work-piece, a cylinder, a two-part piston in the cylinder, springs holding the parts of the piston separated, means operated by relative movement of the piston and cylinder for applying pressure to the work-piece, and liquid in said cylinder, said springs being adapted to be compressed upon application of substantially maximum pressure to the piston through the liquid and to expand thereby maintaining the pressure substantially constant notwithstanding compression of the work or leakage of liquid from the cylinder.

2. In a machine for applying pressure to workpieces, the combination of a support to receive a. Work-piece, a cylinder, a two-part piston in the cylinder, liquid in the cylinder, means acting to apply pressure to the work-piece on the support upon relative movement of the piston and cylinder due to pressure applied through the liquid, means permitting limited relative movement between the two parts of the piston, and a series of springs seated in holes in one of the parts and bearing against the other, said springs being compressed upon application of substantially maximum liquid pressure to the piston and expanding to maintain the pressure substantially constant notwithstanding compression of the work-piece to which pressure is applied by the piston or leakage of the liquid from the cylinder.

3. In a machine for applying pressure to workpieces, the combination of a support toreceive a work-piece, a cylinder, a two-part piston in the cylinder, means operated by relative movement of the piston and cylinder for applying pressure to the work-piece, liquid in said cylinder, a bolt arranged centrally of the two parts of said piston and permitting limited separation thereof, and a series of springs seated in holes in one of the parts and bearing against the other part, said springs being adapted to be compressed when pressure applied to the liquid in the cylinder is approaching its maximum, the springs expanding to maintain the pressure substantially constant in case the Work-piece towhich pressure is being applied becomes compressed or the volume of liquid in the cylinder diminishes.

4. In a machine for applying pressure to workpieces, the combination of a support to receive a work-piece, a cylinder, a two-part piston in the cylinder, means operated by relative movement of the piston and cylinder for applying pressure to the work-piece, liquid in said cylinder, a bolt passing centrally through the two parts of said piston to limit their separation, and a series of springs seated in holes in one of the parts and bearing against the other part, said springs being adapted to be compressed upon application of pressure by the liquid to the piston and to expand to maintain the pressure substantially constant notwithstanding compression of the work-piece to which pressure is being applied or leakage of liquid from the cylinder.

5. In a machine for applying pressure to shoe bottoms, the combination of a pad to receive a shoe, a cylinder, a piston in the cylinder, liquid in the cylinder, means for transmitting pressure from the piston to the shoe on the pad, said piston comprising an upper part loosely fitting the cylinder and having a central hole therethrough and a series of holes parallel to the central hole but not passing through said piston part, springs seated in said holes and projecting beyond the end of said piston part, a second piston part tightly fitting the cylinder and having a central hole, and a bolt passing through the central hole of both piston parts thus retaining the springs in place in the upper part of the piston and holding them under tension, the arrangement being such that the bolt and the first-mentioned part of the piston are relatively movable lengthwise of the cylinder to permit compression of the springs when pressure is applied by the liquid to the piston, the springs reacting to maintain the pressure in case the volume of liquid in the cylinder is reduced or the shoe is compressed.

6. In a machine for applying pressure to shoe bottoms, the combination of a pad to receive the shoe, a cylinder, a two-part piston in the cylinder, compression springs between the parts of the piston, means connected to the piston for applying pressure to the shoe on the pad, and a liquid in said cylinder, pressure of said liquid acting to compress said springs and apply pressure to the work, the springs reacting substantially to maintain pressure on the work in case of liquid leaking from the cylinder or of compression of the shoe parts.

7. In a machine for applying pressure to shoe bottoms, the combination of a pad to receive the shoe, a cylinder, a two-part piston in the cylinder, one part being a sliding fit in the cylinder and the other part being fluid tight in the cylinder, compression springs between the parts of the piston, means connected to the first-mentioned part of the piston for applying pressure to the shoe on the pad, and a liquid in said cylinder, pressure of said liquid acting to compress said springs when the pressure is at a maximum and to apply pressure to the work, the springs reacting to maintain substantially maximum pressure on the work in case of liquid leaking from the cylinder or of compression of the shoe parts.

HERBERT B. NEWHALL. 

